eryksun added the comment:
Albert, this issue was opened for Python 2.4 and was closed over 6 years ago.
Open a new issue if you believe there's a bug or room for improvement in a
currently supported Python version.
FYI, on Windows _PyOS_URandom first initializes the Crypto API by calling
[CryptAcquireContext][1]. As shown in the debug session below, this function
requires the SystemRoot environment variable to be correctly defined.
C:\>cdb -g "C:\Program Files\Python27\python.exe"
Microsoft (R) Windows Debugger Version 6.12.0002.633 AMD64
Copyright (c) Microsoft Corporation. All rights reserved.
...
>>> import os
>>> from ctypes import *
...
>>> PROV_RSA_FULL = 1
>>> CRYPT_VERIFYCONTEXT = 0xf0000000
>>> CryptAcquireContextA = WinDLL('advapi32').CryptAcquireContextA
>>> hcrypt = c_void_p()
>>> del os.environ['SystemRoot']
>>> CryptAcquireContextA(byref(hcrypt), None, None, PROV_RSA_FULL,
CRYPT_VERIFYCONTEXT)
ModLoad: 000007fe`fc480000 000007fe`fc498000
C:\Windows\system32\CRYPTSP.dll
CryptAcquireContext: CheckSignatureInFile failed at cryptapi.c line 5198
CryptAcquireContext: Failed to read registry signature value at cryptapi.c
line 873
0
>>> os.environ['SystemRoot'] = 'C:\\Windows'
>>> CryptAcquireContextA(byref(hcrypt), None, None, PROV_RSA_FULL,
CRYPT_VERIFYCONTEXT)
ModLoad: 000007fe`fc180000 000007fe`fc1c7000
C:\Windows\system32\rsaenh.dll
ModLoad: 000007fe`fcae0000 000007fe`fcaef000
C:\Windows\system32\CRYPTBASE.dll
1
>>> hcrypt
c_void_p(4407952L)
It has always struck me as odd that this API uses the environment variable
instead of the object manager's secured \SystemRoot object symbolic link. C'est
la vie.
Anyway, I don't think Python's os and subprocess modules should prevent you
from shooting yourself in the foot here. When creating an environment block for
a child process, excluding SystemRoot is generally a bad idea, but the language
shouldn't get in the way.
I think it's prudent to include at least all of the system-defined variables.
Here's a function that calls [CreateEnvironmentBlock][2] and returns the system
variables in a dict. It excludes user variables and doesn't inherit from the
current process.
import ctypes
userenv = ctypes.WinDLL('userenv', use_last_error=True)
def errcheck_bool(result, func, args):
if not result:
raise ctypes.WinError(ctypes.get_last_error())
return args
userenv.CreateEnvironmentBlock.argtypes = (ctypes.POINTER(ctypes.c_void_p),
ctypes.c_void_p,
ctypes.c_int)
userenv.DestroyEnvironmentBlock.argtypes = (ctypes.c_void_p,)
def get_system_environ():
WCHAR_SIZE = ctypes.sizeof(ctypes.c_wchar)
environ = {}
cenv = ctypes.c_void_p()
userenv.CreateEnvironmentBlock(ctypes.byref(cenv), None, 0)
addr = cenv.value
try:
while True:
s = ctypes.c_wchar_p(addr).value
if not s:
break
i = s.find('=', 1)
if i != -1:
environ[s[:i]] = s[i+1:]
addr += (len(s) + 1) * WCHAR_SIZE
finally:
userenv.DestroyEnvironmentBlock(cenv)
return environ
[1]: https://msdn.microsoft.com/en-us/library/aa379886
[2]: https://msdn.microsoft.com/en-us/library/bb762270
----------
nosy: +eryksun
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